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Villigen, Switzerland

The Paul Scherrer Institute is a multi-disciplinary research institute which belongs to the Swiss Federal Institutes of Technology Domain covering also the ETH Zurich and the EPFL. It was established in 1988 by merging in 1960 established EIR and in 1968 established SIN . Currently, it is based in Villigen and Würenlingen.The PSI is a multi-disciplinary research centre for natural science and technology. In national and international collaboration with universities, other research institutes and industry, PSI is active in solid state physics, materials science, elementary particle physics, life science, nuclear and non-nuclear energy research, and energy-related ecology.It is the largest Swiss national research institute with about 1,400 members of staff, and is the only one of its kind in Switzerland.PSI is a User Laboratory and runs several particle accelerators. The 590MeV cyclotron, with its 72MeV companion pre-accelerator, is one of them. As of 2011, it delivers up to 2.2mA proton beam, which is the world record for such proton cyclotrons. It drives the spallation neutron source complex. The Swiss Light Source , built in 2001, is a synchrotron light source with a 2.4GeV electron storage ring. It is one of the world's best with respect to electron beam brilliance and stability. An X-ray free-electron laser called SwissFEL is currently under construction and is slated to begin operation in 2016.The proton accelerators are also used for the proton therapy program. Wikipedia.

Vaz C.A.F.,Paul Scherrer Institute
Journal of Physics Condensed Matter | Year: 2012

We review the recent developments in the electric field control of magnetism in multiferroic heterostructures, which consist of heterogeneous materials systems where a magnetoelectric coupling is engineered between magnetic and ferroelectric components. The magnetoelectric coupling in these composite systems is interfacial in origin, and can arise from elastic strain, charge, and exchange bias interactions, with different characteristic responses and functionalities. Moreover, charge transport phenomena in multiferroic heterostructures, where both magnetic and ferroelectric order parameters are used to control charge transport, suggest new possibilities to control the conduction paths of the electron spin, with potential for device applications. © 2012 IOP Publishing Ltd.

Furrer A.,Paul Scherrer Institute | Waldmann O.,Albert Ludwigs University of Freiburg
Reviews of Modern Physics | Year: 2013

Magnetic clusters, i.e., assemblies of a finite number (between two or three and several hundred) of interacting spin centers which are magnetically decoupled from their environment, can be found in many materials ranging from inorganic compounds and magnetic molecules to artificial metal structures formed on surfaces and metalloproteins. Their magnetic excitation spectra are determined by the nature of the spin centers and of the magnetic interactions, and the particular arrangement of the mutual interaction paths between the spin centers. Small clusters of up to four magnetic ions are ideal model systems in which to examine the fundamental magnetic interactions, which are usually dominated by Heisenberg exchange, but often complemented by anisotropic and/or higher-order interactions. In large magnetic clusters, which may potentially deal with a dozen or more spin centers, there is the possibility of novel many-body quantum states and quantum phenomena. In this review the necessary theoretical concepts and experimental techniques to study the magnetic cluster excitations and the resulting characteristic magnetic properties are introduced, followed by examples of small clusters, demonstrating the enormous amount of detailed physical information that can be retrieved. The current understanding of the excitations and their physical interpretation in the molecular nanomagnets which represent large magnetic clusters is then presented, with a section devoted to the subclass of single-molecule magnets, distinguished by displaying quantum tunneling of the magnetization. Finally, there is a summary of some quantum many-body states which evolve in magnetic insulators characterized by built-in or field-induced magnetic clusters. The review concludes by addressing future perspectives in the field of magnetic cluster excitations. © 2013 American Physical Society.

Detailed temporal consideration has been a major challenge for energy systems models with typical time horizons of years and decades. This presents particular issues in investigating electricity generation, capacity and storage, whilst retaining broader trade-offs sectors, technology pathways and timing of investments. This paper reports on a methodology for temporal disaggregation in the widely applied energy service driven, technology rich, cost optimizing, linear programming MARKAL energy system model. A flexible time slicing feature is developed to enhance representation of diurnal and seasonal electricity demand curves through disaggregation of resource availability and energy service demands. In a first application of a temporal UK MARKAL model, a range of runs investigate the role of electricity storage at supply and demand sides. The results display considerably enhanced insights, notably on the role and preference of demand-side electricity storage over supply-side storage. On average, the system chooses about 7-10% of electricity demand as storage. On the supply side, hydrogen-based electricity storage is greatly preferred but stored-hydrogen is used in the transport sector rather than for power system balancing mechanism. © 2010 Elsevier Ltd.

Deupi X.,Paul Scherrer Institute
Biochimica et Biophysica Acta - Bioenergetics | Year: 2014

Rhodopsin, the dim-light photoreceptor present in the rod cells of the retina, is both a retinal-binding protein and a G protein-coupled receptor (GPCR). Due to this conjunction, it benefits from an arsenal of spectroscopy techniques that can be used for its characterization, while being a model system for the important family of Class A (also referred to as "rhodopsin- like") GPCRs. For instance, rhodopsin has been a crucial player in the field of GPCR structural biology. Until 2007, it was the only GPCR for which a high-resolution crystal structure was available, so all structure-activity analyses on GPCRs, from structure-based drug discovery to studies of structural changes upon activation, were based on rhodopsin. At present, about a third of currently available GPCR structures are still from rhodopsin. In this review, I show some examples of how these structures can still be used to gain insight into general aspects of GPCR activation. First, the analysis of the third intracellular loop in rhodopsin structures allows us to gain an understanding of the structural and dynamic properties of this region, which is absent (due to protein engineering or poor electron density) in most of the currently available GPCR structures. Second, a detailed analysis of the structure of the transmembrane domains in inactive, intermediate and active rhodopsin structures allows us to detect early conformational changes in the process of ligand-induced GPCR activation. Finally, the analysis of a conserved ligand-activated transmission switch in the transmembrane bundle of GPCRs in the context of the rhodopsin activation cycle, allows us to suggest that the structures of many of the currently available agonist-bound GPCRs may correspond to intermediate active states. While the focus in GPCR structural biology is inevitably moving away from rhodopsin, in other aspects rhodopsin is still at the forefront. For instance, the first studies of the structural basis of disease mutants in GPCRs, or the most detailed analysis of cellular GPCR signal transduction networks using a systems biology approach, have been carried out in rhodopsin. Finally, due again to its unique properties among GPCRs, rhodopsin will likely play an important role in the application of X-ray free electron laser crystallography to time-resolved structural biology in membrane proteins. Rhodopsin, thus, still remains relevant as a model system to study the molecular mechanisms of GPCR activation. This article is part of a Special Issue entitled: Retinal Proteins - You can teach an old dog new tricks. © 2013 Elsevier B.V.

Gautier A.,Paul Scherrer Institute
Biochimica et Biophysica Acta - Bioenergetics | Year: 2014

The biochemical processes of living cells involve a numerous series of reactions that work with exceptional specificity and efficiency. The tight control of this intricate reaction network stems from the architecture of the proteins that drive the chemical reactions and mediate protein-protein interactions. Indeed, the structure of these proteins will determine both their function and interaction partners. A detailed understanding of the proximity and orientation of pivotal functional groups can reveal the molecular mechanistic basis for the activity of a protein. Together with X-ray crystallography and electron microscopy, NMR spectroscopy plays an important role in solving three-dimensional structures of proteins at atomic resolution. In the challenging field of membrane proteins, retinal-binding proteins are often employed as model systems and prototypes to develop biophysical techniques for the study of structural and functional mechanistic aspects. The recent determination of two 3D structures of seven-helical trans-membrane retinal proteins by solution-state NMR spectroscopy highlights the potential of solution NMR techniques in contributing to our understanding of membrane proteins. This review summarizes the multiple strategies available for expression of isotopically labeled membrane proteins. Different environments for mimicking lipid bilayers will be presented, along with the most important NMR methods and labeling schemes used to generate high-quality NMR spectra. The article concludes with an overview of types of conformational restraints used for generation of high-resolution structures of membrane proteins. This article is part of a Special Issue entitled: Retinal Proteins - You can teach an old dog new tricks.

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